Abstract: Anew approach for measuring association number (i) and associated degree (a) in species solution is presented.Selection of different values of i will yield curve with differing shape, but only the correct value of i will yield a straight line with slope p and intercept of ε_M.The value of a can be obtained from spectrophotometric data through the equation.The systems of bipyridine in cyclohexane and rhodamine 6Gin water are used to demonstrate the applicability of the method, it has been applied to the determination of i and α with satisfactory results.This paper describes the effect of rhodamine 6Gmonomer solution on recovering of fluorescence more effectively to the dimer solution.Rhodamine 6Gdimerizes in higher concentration range in aqueous solution and its fluorescence fades remarkably.In the case, the variation of R 6Gfluorescence intensity implies that the process from dimer to monomer is D→2M; M_i→M+(i-1.)Min water medium.

Key words: Association number, Associated degree, Spectrophotometry, Bipyridine, Rhodamine6G